1. Field of the Invention
The invention generally relates to a display system, and more particularly, to a multi-resolution display system.
2. Description of Related Art
Due to the increasing demand for space efficiency, digital desk that can carry out word processing tasks and display digital images has become one of the new trends. Mark Ashdown published an article titled “The Escritoire: A Personal Projected Display for Interacting with Documents” in 2002, where a digital file is projected onto a desk by using a projection device and a reflective mirror. In this technique, the design of the entire system is adjusted by taking the special structure of human vision into consideration. Human vision includes foveal vision and peripheral vision. Foveal vision is also referred to as direct vision, and which is suitable for identifying details in images and color information but is not suitable for identifying shadows. However, peripheral vision is good at shadow identification. Thus, if one gazes at an object intensely, the effect of peripheral vision gradually decreases as time goes on. For example, when one stares at one character among many characters of a letter more and more intensely, the other characters in the letter will gradually blur off.
Based on the special structure of human vision, two projectors are disposed in a conventional digital desk system. One of the projectors projects images that have larger sizes and are blurrier (of lower resolutions), while the other projector projects images that have smaller sizes and are sharper (of higher resolutions). In order to carry out operations (for example, to move digital files), this system provides pens of two different detection systems. Because these two detection systems should not interfere with each other, one of the pens is an ultrasonic pen and the other pen is an electromagnetic pen. Herein the ultrasonic pen is used for moving digital files, and the electromagnetic pen is used for writing to files.
However, in such a conventional digital desk system, because the projection sources are all placed on top or in front of the desk, the entire system takes up a large space. Meanwhile, with such a projection source design, when a user writes or operates, the displayed image may be blocked by and accordingly projected onto the user's arm so that some viewers may not be able to view the displayed image comfortably. Additionally, because all the high-resolution projection devices are fixed to specific positions, it is impossible to display high-resolution images in other areas, which reduces the flexibility in the operation of the digital desk system.
In Tabletop Conference 2008, Ting-Ting Hu and his partners released a multi-resolution digital desktop display system. In this system, a peripheral projection device and a foveal projection device for presenting images are disposed below the desk, so as to reduce the space taken up by the entire system. Meanwhile, images are projected from below the desk so that the presented images are prevented from being blocked by a user's arm. However, in such a design, because the projection equipments and the desk have an integral design, it is impossible to add new projection equipment below the desk or present multiple high-resolution images.
A multi-resolution digital desktop display system is disclosed in Taiwan Patent No. 200900831. In this technique, a peripheral projection device and a foveal projection device for presenting images are also disposed below the desk so that it is also impossible to add new projection equipment. Besides, in this multi-resolution digital desktop display system, the projected position of a central image is changed by changing the reflection angle of a reflective mirror with an electric motor. Thus, some restrictions are applied when the projected position of the central image is changed. For example, the projected position of the central image cannot be changed at fixed intervals.